john sexton wrote:

Hi Alberto,
You may not need to. There's hope for us low ERP guys yet, it seems that one
just needs to go slower and slower. What about 300 second dots or 1000
second dots for VK and ZL?
73, John, G4CNN

John,
        you probably wrote that with tongue-in-check :-)
I'm afraid we have already reached the limits of the stability of the sampling 
rate
of ordinary sound cards. Either OCXO-driven external sampling hardware must
be used, or more efficient signalling schemes must be adopted. One such 
candidate
could be the Steve Onley's FDK.  I know that, theoretically, PSK can have an
advantage over non-coherent FSK, but this doesn't take into account phase
distortion over very long paths.  But I will leave to others to discuss about 
the
pros and cons of the two methods.

73  Alberto   I2PHD